Add incoming threads to binder_bpBinderFuzz

If the RpcSession associated with a binder has no incoming threads, then
calling linkToDeath on it is fatal.

Test: binder_bpBinderFuzz
clusterfuzz-testcase-minimized-binder_bpBinderFuzz-6220735032197120
Bug: 239917056

Change-Id: I471b72e55c240ac8344ebc8506c32e60c61d13bf
diff --git a/libs/binder/tests/unit_fuzzers/BpBinderFuzz.cpp b/libs/binder/tests/unit_fuzzers/BpBinderFuzz.cpp
index e77c55c..910c9dc 100644
--- a/libs/binder/tests/unit_fuzzers/BpBinderFuzz.cpp
+++ b/libs/binder/tests/unit_fuzzers/BpBinderFuzz.cpp
@@ -49,6 +49,7 @@
     });
 
     sp<RpcSession> session = RpcSession::make();
+    session->setMaxIncomingThreads(1);
     status_t status;
     for (size_t tries = 0; tries < 5; tries++) {
         usleep(10000);